JP5082237B2 - Vehicle steering assist device - Google Patents

Description

  The present invention relates to a vehicle steering assist device that assists a driver's steering so that a vehicle can travel appropriately along the vicinity of the center of a traveling lane.

  In recent years, there has been proposed an apparatus that assists the driver's steering so that the vehicle can appropriately travel along the vicinity of the center of the travel lane (see, for example, Patent Document 1). In this type of steering assist device, an image ahead of the traveling direction of the host vehicle is captured by a CCD camera or the like, and a white line (road marking line) that divides the traveling lane of the host vehicle is detected from the captured image by image recognition processing. A steering direction and a steering torque for allowing the host vehicle to travel along the vicinity of the center of the travel lane divided by the detected white line (road lane line) are obtained, and the steering torque corresponding to the steering direction is obtained by steering the vehicle. By giving it to the mechanism, the steering of the driver is supported.

Here, in Patent Document 1, in order to accurately drive a vehicle along the vicinity of the center of the travel lane, the curvature of the curve of the travel lane, the amount of lateral displacement of the center line of the vehicle with respect to the center line of the travel lane (offset) ) And calculating the steering torque using the vehicle deflection angle formed by the center line of the vehicle with respect to the center line of the traveling lane.
JP 2001-10518 A

  By the way, the frictional resistance of the rack / pinion mechanism, suspension joint, etc. works as steering resistance in the steering mechanism of the vehicle, so the steering resistance of the steering mechanism is anticipated when steering assistance is performed by turning the steering wheel to increase the steering wheel. It is necessary to apply a steering torque to the steering mechanism. However, in steering assistance that returns the steered state so as to switch back the steering wheel, the force that attempts to return the vehicle wheels to the straight traveling state acts on the steering mechanism from the road surface, so the steering resistance of the steering mechanism is reduced. If the expected steering torque is applied to the steering mechanism as it is, the steering torque for steering assistance becomes excessive.

  In order to solve such a problem, the applicant of the present invention has made a steering torque amount at the time of steering support for turning the steering wheel to increase the steering wheel and a steering wheel for returning the steering state to switch back the steering wheel. Steering state with a predetermined hysteresis width between the steering torque amount at the time of assistance and turning the steering wheel back more than the steering torque amount at the time of steering assistance by turning the steering wheel to increase the steering wheel Has developed a technology for setting a small amount of steering torque at the time of steering support for returning the vehicle to the vehicle, and has proposed the contents thereof by a patent application.

  Here, when the vehicle passes the curved part of the driving lane, when the driver intentionally turns the steering wheel so that it passes inside the curved part and turns the steering wheel, the steering wheel is turned back to A steering torque intended to be directed to the outside of the curved portion is applied to the steering mechanism as steering assistance. That is, even though the driver intentionally turns the steering wheel while turning, the steering torque as steering assistance switches back the steering wheel in the opposite direction, so the driver feels uncomfortable with the steering feeling.

  Then, this invention makes it a subject to provide the steering assistance apparatus for vehicles which can improve the steering feeling at the time of a driver | operator's intentionally turning operation.

The steering assist device for a vehicle according to the present invention turns the steering wheel so that the steering wheel is increased when the steering mechanism is given to the steering mechanism of the vehicle so that the vehicle travels along a predetermined position of the traveling lane. A steering assist device for a vehicle in which the steering at the time of steering assistance that returns the steered state so that the steering wheel is turned back is set smaller than the steering at the time of steering assistance, and the curve of the traveling lane is A means for detecting the direction and a means for detecting the steering direction of the driver, and when the steering direction of the driver coincides with the direction of the curve of the traveling lane, the steering wheel is turned to increase the steering wheel. It is characterized in that the steering at the time of steering assistance is provided to the steering mechanism of the vehicle.

  In the vehicle steering assist device according to the present invention, when the steering direction of the driver coincides with the direction of the curve of the traveling lane, that is, the driver intentionally increases the steering wheel in the direction of the curve of the traveling lane and turns the steering. When operating, since steering at the time of steering assistance for turning the steering wheel to increase the steering wheel is given to the steering mechanism of the vehicle, a steering feeling without a sense of incongruity is obtained as a steering feeling of the driver. .

  In the vehicle steering assist device according to the present invention, when the driver's steering direction coincides with the direction of the curve of the traveling lane, switching to the steering assist that returns the steered state so as to switch back the steering wheel is performed. It is preferable to prohibit. In this case, since the steering at the time of steering assistance that turns the steering wheel to increase the steering wheel is surely given to the steering mechanism of the vehicle, a steering feeling without a sense of incongruity is surely obtained as the steering feeling of the driver.

  In the vehicle steering assist device according to the present invention, the steering torque at the time of the steering assist in which the steering is turned to increase the steering wheel, assuming that the provision of the steering for the steering assist is the provision of the steering torque. It is preferable that the characteristic curve of the steering torque and the characteristic curve of the steering torque at the time of steering assistance for returning the steered state so as to switch back the steering wheel are set as a characteristic curve having a predetermined hysteresis width.

  Furthermore, the vehicle steering assist device according to the present invention provides a steering assist for returning the steered state so as to switch back the steering wheel when the driver's steering direction coincides with the direction of the curve of the traveling lane. A steering assist steering torque set larger than the steering torque can be applied. In this case, when the driver intentionally turns the steering wheel in the direction of the curve of the driving lane and performs the steering operation, the steering state is restored so that the steering state is restored so that the steering wheel is turned back. Since a steering assist steering torque that is set larger than the steering torque is applied, a steering sensation with less discomfort can be obtained as the steering sensation of the driver.

  In the vehicle steering assist device according to the present invention, when the driver's steering direction matches the direction of the curve of the traveling lane, the provision of steering assist steering is set larger than when the driver does not match, for example, When the driver intentionally turns the steering wheel in the direction of the curve of the traveling lane and performs a steering operation, the steering assist steering set to a large value is given. Therefore, according to the present invention, it is possible to obtain a steering sensation with no sense of incongruity as a steering sensation when the driver is intentionally turning, and the steering sensation can be improved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a vehicle steering assistance device according to an embodiment of the invention will be described with reference to the drawings. In this description, the same or similar components are denoted by the same reference numerals, and redundant description may be omitted. Here, in the drawings to be referred to, FIG. 1 is a perspective view showing a vehicle to which the vehicle steering assist device according to the embodiment is applied and its traveling lane, and FIG. 2 is a configuration of the vehicle steering assist device according to the embodiment. It is a schematic diagram which shows the outline | summary.

  As shown in FIG. 1, the vehicle steering assist device according to the embodiment travels along the vicinity of the center of a travel lane TL in which the vehicle 1 is basically partitioned by left and right white lines (road marking lines) LL and LR. This is a device that assists in steering, and is provided with a CCD camera 2 that images a traveling lane TL ahead of the traveling direction of the vehicle 1, for example, on the back side of the room mirror 3 of the vehicle 1.

  Further, as shown in FIG. 2, the vehicle steering assist device acquires various parameters relating to the curve state of the travel lane TL and the position and posture of the vehicle 1 from image data captured by the CCD camera 2. A torque sensor 6 for detecting a steering torque applied to a steering shaft of a steering mechanism, which will be described later, a vehicle speed sensor 7 for detecting the traveling speed of the vehicle 1, and a yaw rate sensor 8 for detecting the angular velocity of the yaw angle of the vehicle 1. I have.

  Further, the vehicle steering assist device includes, for example, an ECU (Electric Control Unit) 9 that is a microcomputer that inputs and processes various signals from the image processing unit 4, the torque sensor 6, the vehicle speed sensor 7, and the yaw rate sensor 8. And a motor driver 10 to which a predetermined steering assist signal is input from the ECU 9.

  The ECU 9 executes an input / output interface I / O and an A / D converter, a ROM (Read Only Memory) storing a program and data, a RAM (Random Access Memory) temporarily storing input data, and the program. A CPU (Central Processing Unit) or the like is provided as hardware.

  In such a vehicle steering assist device, the motor driver 10 outputs a predetermined drive current to the steering assist assist motor 5A incorporated in the steering mechanism 5 so that the vehicle 1 basically travels along the lane. Steering assistance is performed so as to travel along the vicinity of the center of the TL (see FIG. 1).

  Here, the above-described CCD camera 2 converts the image information of the captured travel lane TL into digital image data by AD (Analog to Digital) conversion and outputs the digital image data to the image processing unit 4. Then, the image processing unit 4 performs a series of image recognition processing such as edge detection processing on the digital image data input from the CCD camera 2, thereby white lines LL and LR (see FIG. 1) that divide the driving lane TL. )

  The image processing unit 4 detects, for example, the curvature x of the curve of the traveling lane TL shown in FIG. 3 by a series of conventionally known image recognition processes based on the information of the recognized white lines LL and LR. For example, the radius R of the curve is geometrically determined by referring to the lateral displacement amount of the white lines LL and LR in front of the vehicle 1 at a predetermined distance and the inclination of the tangent lines of the white lines LL and LR in front of the vehicle 1 at a predetermined distance. The curvature x of the curve is detected as the reciprocal of the radius R of the curve. That is, the image processing unit 4 functions as means for detecting the direction of the curve of the travel lane TL.

  The image processing unit 4 also includes the lane offset D of the vehicle 1 with respect to the travel lane TL (the amount of lateral displacement of the center of the vehicle 1 with respect to the center line LC of the travel lane TL) and the yaw angle θ of the vehicle 1 with respect to the travel lane TL. (An intersection angle with the center line 1C extending in the front-rear direction of the vehicle 1 with respect to the tangent TC of the center line LC of the traveling lane TL) is detected by a series of conventionally known image recognition processes.

  The steering mechanism 5 shown in FIG. 2 includes a rack and pinion type steering gear box 5D in which the rotation of the steering wheel 5B is transmitted via the steering shaft 5C. Are connected to knuckle arms 5G and 5G for steering the steering wheels 5F and 5F via tie rods 5H and 5H.

  Here, the steering gear box 5D incorporates a ball screw mechanism (not shown) configured with the rack bar 5E as a screw shaft member. The assist motor 5A described above is incorporated into the steering gear box 5D concentrically with the rack bar 5E so that the nut member of the ball screw mechanism is rotationally driven by the rotor to drive the rack bar 5E in the axial direction. Yes.

  The torque sensor 6 is incorporated in the steering gear box 5D so as to detect the magnitude and direction of the steering torque applied to the steering shaft 5C of the steering mechanism 5, for example. The torque sensor 6 outputs a positive detection signal to the ECU 9 when the steering direction is the right direction, and outputs a negative detection signal to the ECU 9 when the steering direction is the left direction.

  The vehicle speed sensor 7 is a sensor for detecting the traveling speed of the vehicle 1, and is appropriately installed to detect, for example, the rotational speed of the steering wheels 5F, 5F and the rotational speed of a transmission output shaft (not shown). The detected rotation speed is set to the ECU 9 as a pulse signal. The yaw rate sensor 8 is disposed near the center of gravity of the vehicle 1, detects the angular velocity of the yaw angle around the vertical axis passing through the center of gravity of the vehicle 1, and outputs a detection signal to the ECU 9.

  The ECU 9 detects, as means for detecting the steering direction of the driver, the magnitude and steering direction of the steering torque generated by the driver's operation of the steering wheel 5B based on the input signal from the torque sensor 6. The ECU 9 detects the traveling speed of the vehicle 1 based on the input signal from the vehicle speed sensor 7, and calculates the yaw rate that is the angular velocity of the yaw angle around the vertical axis of the vehicle 1 based on the input signal from the yaw rate sensor 8. To detect. Then, the ECU 9 outputs a predetermined steering assistance signal related to the steering torque for steering assistance to the motor driver 10.

  When a predetermined steering assistance signal is input from the ECU 9, the motor driver 10 outputs a drive current corresponding to the steering assistance signal to the assist motor 5 </ b> A of the steering mechanism 5. Thus, the assist motor 5A applies a predetermined steering torque to the steering gear box 5D to assist the left and right axial movement of the rack bar 5E.

  Here, as shown in FIG. 4, the ECU 9 which is a microcomputer has a feedforward controller (F / F) as means for causing the vehicle 1 to travel along the center line LC of the travel lane TL shown in FIG. Controller) 9A, offset coefficient section 9B, yaw angle coefficient section 9C and torque calculation section 9D are configured as software.

  A detection signal of the curvature x of the curve is input from the image processing unit 4 to the F / F controller 9A. The F / F controller 9A calculates the yaw rate ωx necessary for causing the vehicle 1 to travel along the curve of the center line LC of the travel lane TL based on predetermined characteristics according to the curvature x of the curve and the vehicle speed Vn.

The offset coefficient unit 9B includes a target lane offset D ₀ set in advance as a target value of the lane offset D for the vehicle 1 to travel appropriately along the center line LC of the travel lane TL, and the image processing unit 4 A signal (D ₀ −D) that is a deviation ΔD from the output lane offset D is input. The offset coefficient unit 9B calculates the yaw rate ωd for compensating the lane offset D by multiplying the deviation ΔD of (D ₀ -D) by the coefficient Kd.

The yaw angle coefficient unit 9C includes a target yaw angle θ ₀ set in advance as a target value of the yaw angle θ for the vehicle 1 to travel appropriately along the center line LC of the travel lane TL, and the image processing unit 4 A signal of (θ ₀ −θ) that is a deviation Δθ from the yaw angle θ output from is input. The yaw angle coefficient unit 9C calculates a yaw rate ωθ for compensating the yaw angle θ by multiplying the deviation Δθ of (θ ₀ −θ) by a coefficient Kθ.

  The torque calculation unit 9D includes a target yaw rate ω (= ωx + ωd + ωθ) obtained by adding the yaw rate ωx calculated by the F / F controller 9A, the yaw rate ωd calculated by the offset coefficient unit 9B, and the yaw rate ωθ calculated by the yaw angle coefficient unit 9C. ) And a signal of the vehicle speed Vn output from the vehicle speed sensor 7 are input.

  The torque calculator 9D converts the target yaw rate ω into the target lateral acceleration G based on the input vehicle speed Vn, and obtains the steering torque T corresponding to the target lateral acceleration G by map search. Then, the torque calculation unit 9 </ b> D outputs a steering assist signal related to the steering torque T obtained according to the target lateral acceleration G to the motor driver 10.

  As a result, the motor driver 10 outputs a drive current I corresponding to the steering torque T for steering assistance to the assist motor 5A, and the assist motor 5A applies a predetermined steering torque T for steering assistance to the steering gear box 5D. Then, the rack bar 5E is moved in the axial direction. As a result, the steering of the steering wheels 5F and 5F is supported so that the vehicle 1 travels along the center line LC of the travel lane TL.

  Here, the steering torque T obtained by the torque calculation unit 9D by searching the map in accordance with the target lateral acceleration G is a steering mechanism for steering assist by turning the steering wheels 5F and 5F to increase the steering wheel. Therefore, it is necessary to set the steering torque T to a larger value in consideration of the steering resistance due to the frictional resistance of each part 5. On the other hand, in the case of steering assistance that returns the steered state of the steering wheels 5F and 5F so as to switch back the steering wheel, the frictional resistance of the steering mechanism 5 is reduced so that the steering wheels 5F and 5F are returned to the straight traveling state. It is necessary to set a smaller steering torque T.

  Therefore, the steering torque T obtained by the torque calculation unit 9D by map search according to the target lateral acceleration G is set as a characteristic curve as shown in FIG. In other words, the steering torque T at the time of steering support for turning the steering wheels 5F and 5F to increase the steering wheel corresponds to the increase in the absolute value of the target lateral acceleration G as shown by the solid line graph in FIG. Thus, the absolute value of the steering torque T is set to increase. On the other hand, the steering torque T at the time of steering support for returning the steered state of the steering wheels 5F and 5F so as to switch back the steering wheel has a characteristic curve shown by a solid line graph as shown by a dotted line graph in FIG. On the other hand, the characteristic curve is set so that the absolute value of the steering torque T becomes small with a predetermined hysteresis width W.

  In FIG. 5 showing such a characteristic curve, a region where the target lateral acceleration G and the steering torque T are positive is a right-turning region, and a region where the target lateral acceleration G and the steering torque T are negative is a left-turning region. It is. A solid line portion indicated by “R +” indicates a characteristic curve at the time of steering support for turning the steering wheels 5F and 5F to the right so that the steering wheel is increased in the right direction, and a dotted line portion indicated by “R−”. Shows a characteristic curve at the time of steering assistance in which the right turning state of the steering wheels 5F and 5F is returned to the neutral state so that the steering wheel is turned back to the left. On the other hand, a solid line portion indicated by “L +” indicates a characteristic curve at the time of steering support in which the steering wheels 5F and 5F are turned to the left so as to increase the steering wheel in the left direction, and a dotted line portion indicated by “L−” Shows a characteristic curve at the time of steering support in which the left steered state of the steering wheels 5F, 5F is returned to the neutral state so that the steering wheel is turned back to the right.

  Here, in the vehicle steering assist device of the present embodiment, for example, when the vehicle 1 passes through the curve portion of the travel lane TL as shown in FIG. 6, for example, the vehicle 1 is basically the center line of the travel lane TL. Steering assistance is made so that the vehicle travels along the LC, and when the driver intentionally turns the vehicle 1 so as to pass inside the curve portion of the travel lane TL, the steering feeling is improved. Steering assistance to Such steering assist control is executed by the ECU 9 according to the flowcharts shown in FIGS.

  First, as shown in FIG. 7, the ECU 9 sequentially executes a driver right steering determination process, a driver left steering determination process, a steering support forced switching process, a steering support determination process, and a steering torque output process in the main routine of steps S1 to S5. .

  The driver right steering determination process in step S1 is a process for determining whether or not the driver (driver) is intentionally steering the steering wheel 5B in the right direction, and the torque sensor 6 described above. Is executed in accordance with the flowchart of the subroutine shown in FIG.

  First, in step S10, it is determined whether or not a flag Fdsrm, which is the previous value of a flag indicating a situation in which the driver is steering the steering wheel 5B in the right direction, is “OFF”. If this determination result is YES and the driver has not steered the steering wheel 5B in the right direction, in the next step S11, the steering input by the driver is a predetermined positive value based on the input signal from the torque sensor 6. It is determined whether or not the threshold value MT1 is greater than the threshold value MT1. The steering input by the driver is a positive value in the case of right steering and a negative value in the case of left steering.

  If the determination result in step S11 is YES and the steering input by the driver is greater than the threshold value MT1, it is determined that the driver is steering the steering wheel 5B to the right, and the driver right steering is performed in the next step S12. After 1 is added to the timer, the process proceeds to the following step S13.

  On the other hand, if the determination result in step S11 is NO and the steering input by the driver is smaller than the threshold value MT1, it is determined that the driver is not steering the steering wheel 5B to the right, and the driver right steering is performed in step S14. After the timer is reset, the process proceeds to step S13.

  In step S13, it is determined whether the driver right steering timer is greater than T1. If the determination result is YES and the driver right steering timer is greater than T1, the driver recognizes that the right steering state is intentionally continued, and in the next step S15, the driver turns the steering wheel 5B. After the flag Fdsr indicating the situation where the steering is intentionally continued in the right direction is set to “ON”, the flag Fdsr is stored as the flag Fdsrm in the subsequent step S16.

  On the other hand, if the determination result in step S10 is NO and the driver is steering the steering wheel 5B to the right, the steering input by the driver is smaller than the threshold value MT1 based on the input signal from the torque sensor 6 in step S17. It is determined whether or not it is smaller than a threshold value MT2 having a predetermined positive value.

  If the decision result in the step S17 is YES and the steering input by the driver is smaller than the threshold value MT2, it is recognized that the driver is not substantially steering to the right, and the driver pushes the steering wheel 5B in the next step S18. After the flag Fdsr indicating the state of steering to the right is set to “OFF”, the process proceeds to step S16.

  On the other hand, if the decision result in the step S17 is NO and the steering input by the driver is larger than the threshold value MT2, it is determined that the driver is substantially steering to the right and the process proceeds to a step S15. If the determination result in step S13 is NO and the driver right steering timer is smaller than T1, it is determined that the driver does not continue the right steering state, and the process proceeds from step S18 to step S16.

  When the subroutine of the driver right steering determination process shown in FIG. 8 ends, the process returns to the main routine of FIG. 7, and the ECU 9 executes the driver left steering determination process in step S2. The driver left steering determination process is a process for determining whether or not the driver (driver) is intentionally steering the steering wheel 5B leftward. Based on the input signal, the process is executed according to the flowchart of the subroutine shown in FIG.

  First, in step S20, it is determined whether or not a flag Fdslm, which is a previous value of a flag indicating a situation in which the driver is steering the steering wheel 5B leftward, is “OFF”. If this determination result is YES and the driver has not steered the steering wheel 5B in the left direction, in the next step S21, the steering input by the driver is based on the input signal from the torque sensor 6 from the threshold value of −MT1. It is determined whether or not it is small.

  If the decision result in the step S21 is YES and the steering input by the driver is smaller than the threshold value −MT1, the driver recognizes that the steering wheel 5B is steered leftward, and in the next step S22, the driver After adding 1 to the left steering timer, the process proceeds to the following step S23.

  On the other hand, if the determination result in step S21 is NO and the steering input by the driver is greater than the threshold value of −MT1, the driver recognizes that the steering wheel 5B is not steered leftward, and the driver in step S24. After the left steering timer is reset, the process proceeds to step S23.

  In step S23, it is determined whether the driver left steering timer is greater than T1. If the determination result is YES and the driver left steering timer is greater than T1, the driver recognizes that the left steering state is intentionally continued, and the driver pushes the steering wheel 5B in the next step S25. After the flag Fdsl indicating the state of intentionally continuously steering in the left direction is set to “ON”, the flag Fdsl is stored as the flag Fdslm in the subsequent step S26.

  On the other hand, if the determination result in step S20 is NO and the driver is steering the steering wheel 5B leftward, in step S27, the steering input by the driver is based on the input signal from the torque sensor 6, and the threshold value is −MT2. It is judged whether it is larger than.

  If the decision result in the step S27 is YES and the steering input by the driver is larger than the threshold value of −MT2, it is determined that the driver is not substantially left steered, and the driver makes a steering wheel in the next step S28. After the flag Fdsl indicating the situation where 5B is continuously steered in the left direction is set to “OFF”, the process proceeds to step S26.

  On the other hand, when the determination result of step S27 is NO and the steering input by the driver is smaller than the threshold value of −MT2, it is determined that the driver is substantially left steering and the process proceeds to step S25. If the determination result in step S23 is NO and the driver left steering timer is smaller than T1, it is determined that the driver does not continue the left steering state, and the process proceeds from step S28 to step S26.

  When the subroutine of the driver left steering determination process shown in FIG. 9 ends, the process returns to the main routine of FIG. 7, and the ECU 9 executes the steering assist forced switching determination process in step S3. This steering support forced switching determination process is a process for determining whether or not the steering support mode should be forcibly switched from the normal mode to the specific mode, and is executed according to the flowchart of the subroutine shown in FIG. To do.

  First, in step S30, the direction of the curve of the travel lane TL detected by the input signal from the image processing unit 4 is a left curve, and the driver intentionally continuously steers the steering wheel 5B to the left. It is determined whether the flag Fdsl indicating the current status is “ON”.

  If the determination result in step S30 is YES and the driver intentionally continues to steer left in the direction of the left curve of the travel lane TL, the vehicle 1 passes through the inside of the travel curve TL on the left curve. In step S31, the flag Ffdc indicating that the steering assist mode should be forcibly switched is set to “ON”, and the process ends.

  On the other hand, if the determination result of step S30 is NO, the direction of the curve of the travel lane TL detected from the input signal from the image processing unit 4 in step S32 is a right curve, and the driver turns the steering wheel 5B. It is determined whether or not a flag Fdsr indicating a situation where the steering is intentionally continued in the right direction is “ON”.

  If the determination result in step S32 is YES and the driver intentionally continues to steer right in the direction of the right curve of the travel lane TL, the vehicle 1 passes through the inside of the right curve travel lane TL. Thus, after determining that the driver is steering to the right and proceeding to step S31 to set the flag Ffdc indicating that the steering assist mode should be forcibly switched to "ON", the process is terminated.

  On the other hand, if the decision result in the step S32 is NO, a flag Ffdc indicating that the steering assist mode should be forcibly switched is set to “OFF” in a subsequent step S33, and then the process ends.

  When the subroutine of the steering assist forced switching determination process shown in FIG. 10 ends, the process returns to the main routine of FIG. 7, and the ECU 9 executes the steering assist determination process in step S4. This steering assist determination process is a process for determining the steering direction of the steering assist, and is executed according to the subroutine flowchart shown in FIG.

  First, in step S40, the target lateral acceleration G for steering assistance is read by low-pass filter processing, and in the next step S41, whether or not the flag Ffdc indicating that the steering assistance mode should be forcibly switched is “OFF” or not. Determine.

  If the decision result in the step S41 is YES and the flag Ffdc is “OFF”, it is recognized that it is not necessary to forcibly switch the aspect of the steering assist, and the target lateral acceleration G is determined in the subsequent step S42. It is determined whether or not it is smaller than a value obtained by subtracting ΔG from the increase / decrease reference value Glim.

  If the decision result in the step S42 is YES, it is determined that the target lateral acceleration G is sequentially decreased and the vehicle 1 is deviating from the center line LC of the traveling lane TL to the right side, and the steering is performed in the next step S43. The flag Ftgd indicating the steering direction of assistance is set to “left”. In step S44, the reference value Glim is updated with the target lateral acceleration G. In the next step S45, the previous value of the flag Ftgd is updated. Then, the process ends.

  On the other hand, if the determination result in step S42 is NO, it is determined in step S46 whether the target lateral acceleration G is greater than a value obtained by adding ΔG to the increase / decrease reference value Glim. If the determination result is YES, it is determined that the target lateral acceleration G is sequentially increased and the vehicle 1 moves to the left from the center line LC of the travel lane TL, and the steering assist is performed in the next step S47. After the flag Ftgd indicating the steering direction is set to “right”, the process proceeds to step S44. On the other hand, if the determination result of step S46 is NO, the process proceeds to step S45.

  Here, if the determination result in step S41 is NO and the flag Ffdc is not “OFF”, it is determined that it is necessary to forcibly switch the steering support mode, and the steering direction of the steering support is determined in step S48. The flag Ftgd indicating “left or right according to the curve direction of the traveling lane” is set. In step S49, the reference value Glim is updated with the target lateral acceleration G, and then the process proceeds to step S45.

  When the steering assist determination process subroutine shown in FIG. 11 ends, the process returns to the main routine of FIG. 7, and the ECU 9 executes the steering torque output process of step S5. This steering torque output process is executed according to the flowchart of the subroutine shown in FIG.

  First, in step S50, it is determined whether or not the target lateral acceleration G for steering assistance is a positive value greater than or equal to zero. If this determination result is YES and the target lateral acceleration G is the right steering region shown in FIG. 5, it is determined in the next step S51 whether or not the flag Ftgd indicating the steering direction of the steering assist is “right”. To do.

  If the decision result in the step S51 is YES, in the case of steering assistance in the right direction in the right steering area, that is, in the case of steering assistance in which the steering wheels 5F and 5F are steered so as to increase the steering wheel in the right direction. In step S52, the steering torque T corresponding to the target lateral acceleration G is retrieved from the diagram “R +” in FIG.

  In step S53 subsequent to step S52, the ECU 9 outputs a predetermined steering assist signal related to the searched steering torque T to the motor driver 10 to execute an output process of the steering torque T. By this steering torque T output processing, the motor driver 10 outputs a drive current corresponding to the steering assist signal to the assist motor 5A of the steering mechanism 5, and the assist motor 5A applies a predetermined steering torque T to the steering gear box 5D. . As a result, the steering wheels 5F and 5F are steered in a predetermined steering assist direction via the rack bar 5E and the tie rods 5H and 5H.

  On the other hand, if the determination result in step S51 is NO, when steering assistance is performed in the left direction in the right steering area, that is, steering assistance is performed by turning the steering wheels 5F and 5F so as to switch the steering wheel back to the left. In step S54, the steering torque T corresponding to the target lateral acceleration G is retrieved from the diagram "R-" in FIG. 5, and the process proceeds to step S53 to execute the steering torque T output process. To do.

  On the other hand, if the decision result in the step S50 is NO and the target lateral acceleration G is the left steering region shown in FIG. 5, whether or not the flag Ftgd indicating the steering direction of the steering assistance is “left” in the subsequent step S55. Determine whether.

  If the determination result in step S55 is YES, in the case of steering assistance in the left direction in the left steering region, that is, in the case of steering assistance in which the steering wheels 5F and 5F are steered so as to increase the steering wheel in the left direction. In step S56, the steering torque T corresponding to the target lateral acceleration G is retrieved from the diagram “L +” in FIG. 5, and then the process proceeds to step S53 to execute the output process of the steering torque T.

  On the other hand, if the determination result in step S55 is NO, when steering assist is performed in the right direction in the left steering area, that is, steering assist is performed by turning the steering wheels 5F and 5F so as to switch the steering wheel back to the right. In step S57, the steering torque T corresponding to the target lateral acceleration G is retrieved from the diagram "L-" in FIG. 5, and then the process proceeds to step S53 to execute the steering torque T output process. To do.

  Here, as described above, in the vehicle steering assist device of the present embodiment, when the driver intentionally continues the left steering in the direction of the left curve of the traveling lane TL, the steering assist mode is forcibly changed. A flag Ffdc indicating switching should be “ON” (see steps S30 and S31 in FIG. 10), and a flag Ftgd indicating the steering direction of steering assistance is forcibly “left” corresponding to the curve direction of the travel lane TL. 11 (see step S48 in FIG. 11), when the steering torque T is output, the steering torque T corresponding to the target lateral acceleration G is retrieved from the diagram “L +” in FIG. 5 (step S50 in FIG. 12, (See S55 and S56).

  Similarly, when the driver intentionally continues to steer right in the direction of the right curve of the travel lane TL, the flag Ffdc indicating that the steering assist mode should be forcibly switched is set to “ON” (FIG. 10 (see steps S32 and S31), the flag Ftgd indicating the steering direction of the steering assist is forcibly set to “right” according to the direction of the curve of the travel lane TL (see step S48 in FIG. 11). In outputting T, the steering torque T corresponding to the target lateral acceleration G is retrieved from the diagram “R +” in FIG. 5 (see steps S50, S51, and S52 in FIG. 12).

  That is, according to the vehicle steering assist device of the present embodiment, the steering direction of the steering wheel 5B by the driver (driver) coincides with the curve direction of the travel lane TL, and the driver intends in the curve direction of the travel lane TL. When turning the steering wheel with the steering wheel turned on, the steering assist direction is forcibly switched from the original return direction to the turning direction, and the steering is turned to increase the steering wheel. Steering torque at the time of steering assistance is applied to the steering mechanism of the vehicle.

  FIG. 13 shows the time change of the steering torque T at that time. When the direction of the steering assist is the original switchback direction, the steering torque T decreases rapidly as shown by the dotted line graph. To do. On the other hand, according to the steering assist device for a vehicle of the present embodiment, the steering assist direction is forcibly switched from the original switchback direction to the increase direction, so the steering torque T is shown by a solid line graph. To change smoothly. Therefore, it is possible to obtain a steering sensation that does not cause a sense of incongruity as the steering sensation of the driver, and to improve the steering sensation when the driver intentionally performs a steering operation.

  The vehicle steering assist device according to the present invention is not limited to the above-described embodiment. For example, when the steering direction of the steering wheel 5B by the driver matches the direction of the traveling lane TL curve, instead of the steering torque T retrieved according to the target lateral acceleration G from the diagram “R +” or “L +” in FIG. , A separate parallel diagram set between the diagram “R +” and the diagram “R−” or a separate parallel diagram set between the “L +” and the diagram “L−” Alternatively, the steering torque T searched according to the target lateral acceleration G may be applied to the steering mechanism 5.

  In this case, when the driver intentionally turns the steering wheel 5B in the direction of the curve of the traveling lane TL and performs a steering operation, the target lateral acceleration G is obtained from the diagram “R +” or “L +” in FIG. Since a specific steering torque set smaller than the steering torque T searched according to is applied to the steering mechanism 5, a steering sensation with little discomfort can be obtained as the steering sensation of the driver.

  In the present embodiment, the technique of applying the steering torque T as an example of applying the steering to the steering mechanism 5 has been described. However, the technique of the present invention is not limited to the steering torque as giving the steering, but can be controlled based on the steering angle of the steering, the angle of the steering wheel, and the yaw of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a vehicle to which a vehicle steering assist device according to an embodiment of the present invention is applied and a travel lane thereof. It is a mimetic diagram showing an outline of composition of a steering assistance device for vehicles concerning one embodiment. It is a schematic diagram which shows the parameter regarding the position and the advancing direction of the vehicle which drive | work with the parameter of the curve part of the driving lane shown in FIG. FIG. 3 is a block diagram showing a configuration of an ECU shown in FIG. 2. 3 is a graph showing a characteristic curve of steering torque with respect to a target lateral acceleration stored in an ECU shown in FIG. 2. It is a schematic diagram corresponding to FIG. 3 which shows the vehicle which passes a curve part with the curve part of a driving lane. 3 is a flowchart showing a processing routine of a main routine executed by an ECU shown in FIG. It is a flowchart which shows the process sequence of the subroutine of the driver right steering determination process shown in FIG. It is a flowchart which shows the process sequence of the subroutine of the driver left steering determination process shown in FIG. It is a flowchart which shows the process sequence of the subroutine of a steering assistance forced switching process shown in FIG. It is a flowchart which shows the process sequence of the subroutine of the steering assistance determination process shown in FIG. It is a flowchart which shows the process sequence of the subroutine of the steering torque output process shown in FIG. FIG. 7 is a graph showing a change in steering torque T over time due to steering torque output processing when the driver intentionally turns the steering wheel in the curve direction shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... CCD camera, 4 ... Image processing part, 5 ... Steering mechanism, 5A ... Assist motor, 5B ... Steering wheel, 5C ... Steering shaft, 5D ... Steering gear box, 5E ... Rack bar, 5F ... Steering wheel , 6 ... Torque sensor, 7 ... Vehicle speed sensor, 8 ... Yaw rate sensor, 9 ... ECU9, 9A ... F / F controller, 9B ... Offset coefficient part, 9C ... Yaw angle coefficient part, 9D ... Torque calculation part, 10 ... Motor driver , TL ... Traveling lane, LC ... Center line, LL, LR ... White line

Claims (4)

In order to give steering assistance to the steering mechanism of the vehicle so that the vehicle travels along a predetermined position in the traveling lane, the steering wheel is steered to increase the steering wheel. A steering assist device for a vehicle in which the steering at the time of steering support for returning the steered state so as to switch back is set to be small,
Means for detecting the direction of the curve of the driving lane, and means for detecting the steering direction of the driver,
When the driver's steering direction matches the curve direction of the driving lane, the steering mechanism for steering assist by turning the steering wheel to increase the steering wheel is provided to the steering mechanism of the vehicle. A vehicle steering assist device. When the steering direction of the driver coincides with the direction of the curve of the traffic lane, according to claim 1, characterized in that prohibiting switching to the steering assist Yuku by returning the turning state to return off the handle The vehicle steering assist device. The provision of steering for steering assistance is to give steering torque, the steering torque characteristic curve at the time of steering assistance turning the steering wheel to increase, and the steering state to switch back the steering wheel vehicle steering assist apparatus according to claim 1 or 2, the characteristic curve of the steering torque when of Yuku steering assistance is returned is characterized in that it is set as a characteristic curve having a predetermined hysteresis width. When applying steering assist torque to the steering mechanism of the vehicle so that the vehicle travels along a predetermined position in the driving lane, the steering torque is turned to increase the steering wheel. The steering assist device for a vehicle in which a steering torque amount at the time of steering support for returning the steered state so as to switch back the steering wheel is set to be small,
Means for detecting the direction of the curve of the driving lane, and means for detecting the steering direction of the driver,
When the steering direction of the driver coincides with the curve direction of the driving lane, the steering assist steering set to be larger than the steering torque amount at the time of the steering assist for returning the steered state so as to switch back the steering wheel. A steering assist device for a vehicle characterized by applying torque.

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